The present invention is directed to time division multiplex digital information switching systems, and more particularly, to a digital information (voice/data) time slot interchange switch matrix incorporating processor-controlled diagnostic functions that enable on-line/off-line programmable monitoring of redundant switch matrices to identify errors in input and output information, diagnostic and control instructions, and the time slot interchange switching function.
The telecommunications field is currently undergoing rapid technological changes primarily through adapting microprocessor-based data processing technology throughout common carrier and private telecommunication networks. In particular, new central office and private branch exchange switching systems increasingly use digital switching techniques capable of handling both digitized voice and data communications.
At the same time, new data communication systems involving the exchange of all types of data and information in digital form have been developed. Word processing and electronic message systems based upon dispersed microprocessor technology have been developed to supplement traditional data processing, and to provide a more complete scope of services for both standard business offices and large corporations. The tendency has been to design these data-word processing systems independently of communications systems, i.e., word processing systems, data processing systems and telephone exchanges that are self-contained and designed specifically for those respective functions. However, the benefits of integrating communications and data-word processing functions are becoming generally recognized as a means to efficiently manage the generation, transfer, use and storage of business information. Such integrated information communications requires a communication hub or switching system into which the information can flow, be it data, text, voice or messages and be switched to its destination.
One such communication hub is the subject of a patent application entitled DIGITAL INFORMATION SWITCHING SYSTEM, Ser. No. 248,821 (filed Mar. 30, 1981) now U.S. Pat. No. 4,442,502, which is assigned to the assignee of the present invention, Datapoint Corporation, and marketed under the trademark ISX. That digital information switching system combines the features of an information processing system and a telephone private branch exchange in an overall digital system having dispersed processing, flexibility in size and automatic maintenance features. The system provides for dispersed switching architecture featuring modular design with dispersed microprocessor control. Information is switched locally in one of a plurality of remote switching units either for connection between local terminals, or in the case of information to be exchanged between terminals connected to different remote switching units, for transmission to a central switching unit which is connected to each remote switching unit by interswitch links.
For an information communications hub such as the digital information switching system described above, minimizing the risk of system failure is of prime importance. The digital information switching system includes a maintenance/diagnostic processor, running a dedicated diagnostic program, to manage self-diagnostic maintenance procedures that continually monitor each central and remote switching unit. If a problem occurs, the faulty component or circuit board is isolated, electrically disconnected and its spare is automatically brought on-line without outside control. A diagnostic report is then automatically forwarded to a central service center precisely identifying the faulty component. The self-diagnostic maintenance functions incorporated in the digital information switching system are implemented without interruption to calls in progress, even if a malfunction occurs in a critical area, such as one of the system microprocessors, memories or switch matrix.
Regarding the switch matrix, incorporating self-diagnostic functions capable of detecting malfunctions in the following areas would be advantageous to maximize reliability: (a) input PCM data from the various ports, (b) address and control data used in effecting time slot interchange switching, (c) the time slot interchange function, (d) output PCM data after time slot interchange switching, and (e) monitor instructions to the switch matrix received in the course of implementing these diagnostic functions. Moreover, performing these diagnostic functions continuously in a programmable manner on each of redundant on-line/off-line switch matrices, and while each is electrically connected and ready to perform the switching function, also would be advantageous.